ghost touch is software or hardware issue?

Touch is improving in every update so the touch is much better than when device came out at first but there are some oeople who are facing issue like you.
You can try to install beta rom. Beta rom has more improvement on touch than stable since fixes needed to be tested before incorporate in stable rom.
And Head of POCOPHONE Global has mentioned that it is better to visit service center if there is touch problem even in beta roms.